}}I have connected my device Extron to DFROBOT RS232 through to Serial3 of Arduino, Then, I sent this command: ! (admiration), and the device must respond the input selected.But I have no response from the device.When I send the command: !, I see that Rx of DFROBOT light, but doesn't light the TX light. I mean, I don't get response from the Extron device.Can you help me please?Many thanks

Is the bit rate correct?Is the character format (8,n,1) OK for the receiver?

"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.Do not send technical questions via personal messaging - they will be ignored.I speak for myself, not Arduino.

You solve it by using the right tools. Use an oscilloscope to see that your device is sending data to you. You use it also to see that you have got the baud rate right and that the signal is the right way up. It should go to a logic one after it has finished sending stuff.If all that checks out you look again at your software serial stuff and see it is recieving.

How I said in a above message, I connected the device right to a PC and hyperterminal and I get the the message from Extron device.I have no an oscilloscope is to expensive for me. Is there any other to posibility to test it? or oscilloscope software?

Do you know other cheap serial devices to make trying with Arduino and serial?Many thanks

Tell us what equipment you do have, and what equipment you know how to use.

"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.Do not send technical questions via personal messaging - they will be ignored.I speak for myself, not Arduino.